An analytical and applied blasting approach to facilitate rock-socketed bored pile excavation
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ORIGINAL PAPER
An analytical and applied blasting approach to facilitate rock-socketed bored pile excavation Umit Ozer 1 & Abdulkadir Karadogan 1 & Ulku Kalayci Sahinoglu 1 & Meric Can Ozyurt 1 & Zeynep Sertabipoglu 1 & Mustafa Kemal Günay 2 & İbrahim Sefer 2 & Cevdet Burkay Zaif 2 Received: 13 December 2019 / Accepted: 4 June 2020 # Saudi Society for Geosciences 2020
Abstract Conventional bored piling excavation technique in a rock formation is a time-consuming and costly operation due to excavation speed. Blasting can be a useful method for the reduction of rock strength before bored pile excavation by breaking the rock in an area as large as the bored pile diameter. In this way, the drawbacks of pile driving operation can be minimized in terms of project time and cost. In this study, the usability of blasting was investigated in order to increase the speed of conventional bored piling excavation. For this aim, an analytical method based on the airy stress function was established to determine the fragmentation zone that provides sufficient fragmentation to facilitate the bored pile excavation operation in a motorway cut and cover tunnel project. In the model, the detonation pressure, the tensile strength of rock, explosive properties, and drill hole diameter were taken into consideration. The developed model was tested by three different blasting designs and a non-blasting excavation to verify its applicability for the bored pile excavation in the site. As a result, the suggested blasting method can be used in rock-socketed bored pile driving studies to obtain a fragmentation zone as much as pile diameter in order to increase excavation speed and reduce cost and to provide expected excavation performance. This study introduced a first in the literature that the blasting technique was used as the first stage of bored pile excavation. In addition, the developed method can be applied by revising according to different rock conditions and it can be used as a basic pre-design approach. Keywords Blast-supported pile driving . Bored pile excavation . Fragmentation zone . Blasting design . Analytical model
Introduction Bored piles are a commonly used form of building foundation that provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics. Over the years, many researchers have studied bored piles and bored pile excavation applications and tunneling in order to develop new methods to strengthen the grounds at a lower cost, in a shorter time (Gamil et al. 2017; Dao and Pham 2018; Pronozin et al. 2019; Xue and Zhang 2019; Maddah and Soroush 2019).
Responsible Editor: Zeynal Abiddin Erguler * Umit Ozer [email protected] 1
Department of Mining Engineering, Istanbul University-Cerrahpaşa, 34320 Avcilar, Istanbul, Turkey
2
KRP Construction Company, Istanbul, Turkey
In bored pile excavation applications, at first, rock formations have to be drilled and excavated before the installation of bored piles. Drilling of h
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